The ATM gene (Ataxia Telangiectasia Mutated) is a large and complex gene located on chromosome 11, coding for a significant protein that plays a crucial role in DNA damage response and cell cycle control.
What is the Structure of the ATM Gene?
The ATM gene is structured as a substantial genetic unit spanning approximately 150 kilobases (kb) on human chromosome 11, specifically at band 11q22.3. It is notable for coding a large protein, a 350 kDa protein consisting of 3056 amino acids, which functions as a critical serine/threonine protein kinase.
Chromosomal Location and Gene Size
The ATM gene is precisely mapped to band q22.3 on the long arm of chromosome 11. Its considerable length, roughly 150 kilobases, underscores the complexity required to encode a protein of its size and functional importance. This extensive genomic region facilitates the intricate regulatory mechanisms governing its expression.
- Chromosomal Position: 11q22.3
- Gene Length: Approximately 150 kilobases (kb)
You can explore more details about its genomic location and features on resources like the NCBI Gene Database or GeneCards.
Exon-Intron Organization
The ATM gene is characterized by a high number of exons, which are the coding segments of the gene, separated by non-coding introns. The longest known transcript variant of ATM contains approximately 63 coding exons. This intricate arrangement allows for sophisticated gene regulation, including alternative splicing, although the primary ATM protein is well-defined.
- Exon Count: The gene typically contains around 63 coding exons.
- Exon Variability: Exons vary in size, contributing to the overall complexity of the gene.
The ATM Protein: A Key Kinase
The protein encoded by the ATM gene is a robust 350 kDa protein, comprising an impressive 3056 amino acids. This protein is a prominent member of the phosphatidylinositol 3-kinase-related kinases (PIKKs) superfamily.
The PIKK superfamily itself encompasses six distinct Ser/Thr-protein kinases that share notable sequence similarity with phosphatidylinositol 3-kinases (PI3Ks), highlighting ATM's critical role in cellular signaling pathways. As a Ser/Thr-protein kinase, ATM phosphorylates specific serine and threonine residues on target proteins, activating downstream signaling cascades essential for maintaining genomic stability.
Key Structural Features of the ATM Gene and Protein
| Feature | Detail |
|---|---|
| Gene Location | Chromosome 11q22.3 |
| Gene Size | ~150 kilobases (kb) |
| Coding Exons | ~63 |
| Protein Size | 350 kDa |
| Amino Acids | 3056 |
| Protein Class | PIKK superfamily, Ser/Thr-protein kinase |
| Relatedness | Sequence similarity to PI3Ks |
Functional Significance
The large and complex structure of the ATM gene directly correlates with its vital functions. The ATM protein acts as a master regulator in the cellular response to DNA double-strand breaks. Upon sensing DNA damage, ATM rapidly activates a network of proteins involved in cell cycle arrest, DNA repair, and apoptosis, thereby safeguarding the integrity of the genome. Its extensive structure allows for diverse protein-protein interactions and precise enzymatic activity, critical for coordinating these complex cellular processes.
